Quaternary ammonium cation

Quaternary ammonium cation. The R groups may be the same or different alkyl or aryl groups. Also, the R groups may be connected.

Quaternary ammonium cations, also known as quats, are positively charged polyatomic ions of the structure NR4+, R being an alkyl group or an aryl group.[1] Unlike the ammonium ion (NH4+) and the primary, secondary, or tertiary ammonium cations, the quaternary ammonium cations are permanently charged, independent of the pH of their solution. Quaternary ammonium salts or quaternary ammonium compounds (called quaternary amines in oilfield parlance) are salts of quaternary ammonium cations with an anion.

In contrast to phenolics, quaternary ammonium compounds are not very effective in the presence of organic compounds. Yet, they are very effective in combination with phenols. Quaternary ammonium compounds are deactivated by soaps, other anionic detergents, and cotton fibers.[7] Also, they are not recommended for use in hard water. Effective levels are at 200 ppm.[8] They are effective at temperatures up to 212 °F (100 °C).

Quaternary ammonium salts are commonly used in the foodservice industry as sanitizing agents.

Cycocel (chlormequat chloride) reduces plant height by inhibiting the production of gibberellins, the primary plant hormones responsible for cell elongation. Therefore, their effects are primarily on stem, petiole and flower stalk tissues. Lesser effects are seen in reductions of leaf expansion, resulting in thicker leaves with darker green color.[10]

Quaternary ammonium-based disinfectants (Virex and Quatricide) were tentatively identified as the most probable cause of jumps in birth defects and fertility problems in caged lab mice.[15] See also Hunt and Hrubek (Reproductive Toxicology, 50:163-70, 2014).

The quantification of quaternary ammonium compounds in environmental and biological samples is problematic using conventional chromatography techniques because the compounds are highly soluble in water. While analyzing them by liquid chromatography coupled tandem mass spectrometry it has been found that they follow an exception rule. Under standard electrospray ionization (ESI) conditions, mono- and di-quaternary ammonium compounds form molecular ions with the formula of rather than .[clarification needed] Formation of is observed for di-quaternary ammonium compounds (like diquat) as precursor ion and as product ion due to the loss of one of the quaternary charge during CID. In di-quaternary ammonium compounds, this process can also result in the formation of fragment ions with higher mass as compared to their precursor ion. Hydrophilic interaction liquid chromatographic separation has been reported to demonstrate a successful separation of quaternary ammonium compounds for their quantification in ESI-MS/MS with higher precision.[16]